Sms keyboard actuating mechanism with particular feel and contact mechani

ABSTRACT

A plurality of plates and springs are formed in a strip of metal with the springs suspending the plates from the strip. The strip is supported by an insulating support structure which acts as a guide for a plurality of shafts, each shaft being attached to a key. When a key is depressed, the shaft attached to that key displaces a corresponding plate toward one of a plurality of circuit elements on a printed circuit board, which is also fastened to the support structure. An additional shaft is also attached to each key and is guided by the support structure. When a key is depressed the additional shaft deflects a resilient member which exhibits a sudden change in resilience in response to being deflected. This sudden change in resilience provides a tactile signal to the user indicating that the key has been depressed.

United States Patent [1 1 Musch et al.

[4 1 Sept. 4, 1973 KEYBOARD ACTUATING MECHANISM WITH PARTICULAR FEEL AND CONTACT MECHANISMS [75] lnventors: Bernard E. Musch; Donn D. Lobdell,

both of Palo Alto, Calif.

[73] Assignee: Hewlett-Packard Company, Palo Alto, Calif.

[22] Filed: Apr. 15, 1971 211 App]. No.: 134,181

[52] U.S. Cl. 200/159 R, 200/76, 200/166 Bl-l, 200/166 SD [51] Int. Cl ..H01h 13/50, HOlh 3/50, I-lOlh 5/18 [58] Field of Search 200/159 R, 159 A, 200/153 J, 73, 76, 77, 160, 166 SD, 166 BF,

[56] References Cited UNITED STATES PATENTS 2,624,809 l/l953 Sinclaire 200/159 A X 3,274,354 9/1966 Stevens 200/76 3,582,596 6/1971 Woodhead. 200/159 R X 2,986,666 5/1961 Tsutsumi 200/166 BF X 2,697,364 12/1954 Koch; 200/153 J X 3,486,144 12/1969 Paige 200/159 R X 4/1967 Olson 200/ 160 FOREIGN PATENTS OR APPLICATIONS 1,901,469 8/1970 Germany 200/159 A 546,001 3/1956 Belgium ZOO/160 Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye Att0rney-Roland I. Griffin [5 7] ABSTRACT A plurality of plates and springs are formed in a strip of metal with the springs suspending the plates from the strip. The strip is supported by an insulating support structure which acts as a guide for a plurality of shafts, each shaft being attached to a key. When a key is depressed, the shaft attached to that key displaces a corresponding plate toward one of a plurality of circuit elements on a printed circuit board, which is also fastened to the support structure. An additional shaft is also attached to each key and is guided by the support structure. When a key is depressed the additional shaft deflects a resilient member which exhibits a sudden change in resilience in response to being deflected. This sudden change in resilience provides a tactile signal to the user indicating that the key has been depressed.

7 Claims, 8 Drawing Figures Sept. 4, 1973 United States Patent [191 Musch et a].

PATENTEU E 4 75 SHEU 1 BF 3 INVENTORS BERNARD E. MUSCH DONN D LOBDELL PMENTEUSEP W5 I 3.157. 068

sum a nr 3 Iigure 3o.

INVENTORS BERNARD E. MUSCH i ure 3b DONN D. LOBDELL PAIENIED SHEET 3 OF 3 III/III i ure 2a I I I I I ure 2c INVENTORS BERNARD E. MUSCH DONN D. LOBDELL KEYBOARD ACTUATING MECHANISM WITH PARTICULAR FEEL AND CONTACT MECHANISMS BACKGROUND AND SUMMARY OF THE INVENTION board operator to assure him that the key has been depressed sufficiently to effect a contact closure. Those keyboards which do provide, tactile feedback are usually considerably more bulky than those without such feedback. Structurally, most keyboards comprise an array of complex subassemblies which are assembled in a certain configuration at the factory and are usually not field modifiable. These complex subassemblies are usually costly to assemble, making the resultant keyboard relatively expensive.

The actuating mechanism of the present invention provides tactile feedback to the operator, but is more compact than prior art devices with such feedback. A keyboard formed from a combination of a plurality of actuating mechanisms of the instant disclosure and a printed circuit board, of the type hereinafter described, is not only compact, but it can easily be made in modular form so that keys can be added or removed in the field. Since the actuating mechanism comprises relatively few components and the components can be formed in arrays, a keyboard using the "actuating mechanisms of the present invention is inexpensive due to the ease of assembly.

A preferred embodiment of the instant invention comprises a key having a pair of parallel shafts attached to it, one for deflecting a metal plate and the other for actuating a resilient member. The metal plate and a spring attaching it to a metal sheet are formed from the metal sheet, and the metal sheet is attached to an insulating support structure. The support structure also serves as a guide for the shafts. The resilient member may be comprised of a pair of springs of differing spring rates or a single buckled spring which changes resilience suddenly when depressed by the aforementioned shaft. A printed circuit board is attached to the support structure so that the plate is deflected toward a circuit element on the printed circuit board when the key is depressed. The circuit element can be, for example, a sensing element for a noncontacting keyboard of the type described in a copending patent application Ser. No. 74,949 entitled NONCONTACTING KEY- BOARD by David S. Cochran and Glenn E. McGhee, assigned to the assignee of the instant application.

DESCRIPTION OF THE DRAWINGS FIG. 1a shows an exploded view of a preferred embodiment of an actuating mechanism;

FIG. lb shows an alternative printed circuit board for use in the embodiment of FIG. 1a;

FIGS. 2a, 2b, 2c, and 2d show a cut-away view of the operation of one embodiment of the present invention;

FIGS. 3a and 3b show a cut-away view of the operation of another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. la illustrates one of an array of actuating mechanisms. A key 12 is attached to two shafts, l4 and l6, which are guided by holes 18 and 20 in a support member 22. Support member 22 may be a molded plastic part, for example. A metal strip 24 has a metal plate 26 and a pair of springs 28a and 28b formed from it by a process such as chemical etching or stamping. A cantilever 30 is also formed from metal strip 24. Metal strip 24 is held between a spacer 32 and support member 22 and is positioned by locating pins 34. Strip 36, typically made of mylar, is sandwiched between metal strip 24 and support member 22 and is positioned by locating pins parallel to those illustrated. A cantilever 38, part of strip 36, overlies cantilever 30. A printed circuit board 40 is held against spacer 32 by screws 42 which screw into holes in support member 22 (not shown) and hold the whole assembly together. A printed circuit transformer 44 comprising concentric spirals 46 and 48 on both sides of printed circuit board 40 is shown as the sensing element. Transformer 44 is connected to driving and decoding electronics described more fully in the aforementioned copending patent application.

As shown in FIGS. 2a and 20, when key 12 is depressed by a keyboard user, shaft 14 deflects metal plate 26 toward transformer 44, decreasing the mutual inductance between spirals 46 and 48, which provides a key-down signal to the decoding electroncs. Other sensing elements, such as a capacitor, for example, could be used instead of a transformer; or a piece of ferrite could be attached to metal plate 26 to increase the mutual inductance between spirals 46 and 48. Alternatively, as shown in FIG. lb, metal plate 26 can be used to connect a pair of contacts 45 and 47 on printed circuit board 40. When the user releases key 12, springs 28 return metal plate 26 and therefore key 12 to their up positions.

Shaft 16 and cantilevers 30 and 38 are also shown schematically in greater detail in the cut-away view of FIGS. 2a-d. FIG. 2a shows the relative positions of shaft 16 and the cantilevers when key 12 is in the up position. As key 12 is depressed, shaft 16 deflects the two cantilevers as shown in FIG. 2b, and the user encounters increasingly greater resistance. As cantilevers 30 and 38 are deflected downward, tip 39 of cantilever 38 is also deflected laterally so that shaft 16 slides past tip 39. Cantilever 38 then snaps in to a recess 50 in shaft 16 as the key is depressed all the way down. When this happens the user feels the sudden change in resilience as a decrease in the resistance offered by key 12. Shaft 16 encounters resistance only from cnatilever 38 when key 12 is released, as shown in FIG. 2d, since only cantilever 38 extends into recess 50, and springs 28 easily overcome the resistance of cantilever 38 to return key 12 to its up position. Thus the resilience or spring rate of the resilient member comprised of cantilevers 30 and 38 undergoes a sudden change when deflected by shaft 16, and the resilience is different for upward and downward movement of the shaft.

FIG. 3a shows another embodiment of the actuating mechanism. A key 62 is attached to a hollow shaft 64 which is guided by a support member 68. A flexible shaft 66 is also attached to key 62. A buckled spring is fastened between support member 68 and a spacer 72, and it passes through a hole 74 in shaft 64. Attached to spring 70 is a triangular deflector 76, directly under shaft 66. Metal strip 24 including plate 26 and springs 28, but excluding cantilever 30, is sandwiched between spacers 72 and 32. Printed circuit board 40 is attached to spacer 32. When key 62 is depressed, shaft 643 deflects plate 26 toward transformer 44 as previously described. At the same time shaft 66 presses against deflector 76 until spring 70 is deflected far enough to buckle the opposite direction as shown in FIG. 3b. When spring 70 thus buckles, the user feels the sudden change in resilience since the resistance offered shaft 66 by deflector '76 is greatly reduced. When key 62 is released, shaft as, which has also been deflected by deflector 76, will glide along the surface of deflector 76 and will be returned to its upright, straight position by springs 28. Since spring 70 is a bistable element the next time key 62 is depressed, spring 70 will buckle back to the position shown in FIG. 3a.

Although the discussion of FIGS. 1, 2, and 3 has centered on the mechanism associated with a single key, the mechanisms herein disclosed can be advantageously fabricated into multi-element arrays. Thus, as suggested by FIG. 1, a plurality of metal plates 26, springs 28, and cantilevers 34 can be formed in metal strip 24; a plurality of cantilevers 38 can be formed on strip 36; and support member 22; and spacer 32 can be molded to accommodate a plurality of keys. The formation of arrays of constituent components allows a reduction in the assembly time and cost of multielement keyboards. To increase flexibility keys 12 may be retained in support member 22 by a recess 15 in shaft 14 engaging a protrusion in hole 18. Thus keys can be added or removed in the field according to the users needs.

We claim:

1. An actuating mechanism comprising:

a key;

a first and a second shaft attached to the key, the second shaft being parallel to the first shaft and having a notch in one side;

guiding means for guiding the movement of the first and second shafts;

switch means for coacting with the first shaft to give a signal in response to depression of the key by a user; and

resilient means for coacting with the second shaft for exhibiting a sudden change in resilience in response to the movement of the second shaft, the resilient means including cantilever spring means having a first spring rate when deflected in a first direction and a second spring rate when deflected in a second direction and extending into the notch when said key is depressed, thereby providing tactile feedback to the user.

2. An actuating mechanism as in claim 1 wherein the switch means comprises:

a conductive element, a spring and a support member formed from a single piece of material, the conductive element being suspended by the spring from the support member, the conductive element being positioned in line with the first shaft, and the support member being attached to the guiding means; and

a circuit element supported in line with the first shaft and the conductive element;

whereby depression of the key causes the first shaft to displace the conductive element with respect to the circuit element.

3. An actuating mechanism as in claim 1 wherein the cantilever spring means comprises a first and a second overlapping cantilever spring, the first spring having a lower spring rate than the second spring.

4. An actuating mechanism as in claim 1 comprising a plurality of said keys, first and second shafts, switch means, and resilient means for providing an array of key switches.

5. An actuating mechanism as in claim 4 wherein the switch means comprises:

a plurality of conductive elements and springs and a support member formed from a single piece of material; each conductive element being suspended by a spring from the support member, each conductive element being positioned in line with a first shaft and the support member being attached to the guiding means; and

a plurality of circuit elements, each supported in line with a first shaft and corresponding conductive elements, whereby depression of a key causes a first shaft to displace a corresponding conductive element with respect to a corresponding circuit element.

6. An actuating mechanism comprising:

a key;

a first and second shaft attached to the key, the first shaft being hollow and having a hole through it running transverse to the longitudinal axis of the shaft and the second shaft being supported within the first shaft;

guiding means for guiding the movement of the first and second shafts;

switch means for coacting with the first shaft to give a signal in response to depression of the key by a user; and

resilient means for coacting with the second shaft for exhibiting a sudden change in resilience in response to movement of the second shaft, the resilient means including a buckled spring running through the transverse hole in the first shaft and a triangular element fastened to the buckled spring in line with the second shaft, thereby providing tactile feedback to the user.

7. An actuating mechanism as in claim 6 wherein the switch means comprises:

a conductive element, a spring and a support member formed from a single piece of material, the conductive element being suspended by the spring from the support member, the conductive element being positioned in line with the first shaft, and the support member being attached to the guiding means; and

a circuit element supported in line with the first shaft and the conductive element, whereby depression of the key causes the first shaft to displace the conductive element with respect to the circuit element.

-- fIEDsTATES PATENT OFFICE nmin imri: oi (:QRREQTWN Patent No. $7 8 I D ted September 4, 1973 Inventor(s) Bernard E. Musch and Donn D. Lobdell It is certified that error appears in the above-identified patent and that said Letters" Patent are hereby corrected as shown below:

Column 2; line 10, "mylar" should. read Mylar line 26, "electroncs" should read electronics line 49,

"cnatilever" should 'read" cantilever --7 Column lines 22 and 23, "conductive elements," should read jconductive element,

I isi gnedfand sealed this 18th day of December 1973.

(SEAL) Attest:

EDWARD MQFLETCHERJR. RENED. TEGTMEYER Attesting Officer Acting Commissioner of Patents 

1. An actuating mechanism comprising: a key; a first and a second shaft attached to the key, the second shaft being parallel to the first shaft and having a notch in one side; guiding means for guiding the movement of the first and second shafts; switch means for coacting with the first shaft to give a signal in response to depression of the key by a user; and resilient means for coacting with the second shaft for exhibiting a sudden change in resilience in response to the movement of the second shaft, the resilient means including cantilever spring means having a first spring rate when deflected in a first direction and a second spring rate when deflected in a second direction and extending into the notch when said key is depressed, thereby providing tactile feedback to the user.
 2. An actuating mechanism as in claim 1 wherein the switch means comprises: a conductive element, a spring and a support member formed from a single piece of material, the conductive element being suspended by the spring from the support member, the conductive element being positioned in line with the first shaft, and the support member being attached to the guiding means; and a circuit element supported in line with the first shaft and the conductive element; whereby depression of the key causes the first shaft to displace the conductive element with respect to the circuit element.
 3. An actuating mechanism as in claim 1 wherein the cantilever spring means comprises a first and a second overlapping cantilever spring, the first spring having a lower spring rate than the second spring.
 4. An actuating mechanism as in claim 1 comprising a plurality of said keys, first and second shafts, switch means, and resilient means for providing an array of key switches.
 5. An actuating mechanism as in claim 4 wherein the switch means comprises: a plurality of conductive elements and springs and a suPport member formed from a single piece of material; each conductive element being suspended by a spring from the support member, each conductive element being positioned in line with a first shaft and the support member being attached to the guiding means; and a plurality of circuit elements, each supported in line with a first shaft and corresponding conductive elements, whereby depression of a key causes a first shaft to displace a corresponding conductive element with respect to a corresponding circuit element.
 6. An actuating mechanism comprising: a key; a first and second shaft attached to the key, the first shaft being hollow and having a hole through it running transverse to the longitudinal axis of the shaft and the second shaft being supported within the first shaft; guiding means for guiding the movement of the first and second shafts; switch means for coacting with the first shaft to give a signal in response to depression of the key by a user; and resilient means for coacting with the second shaft for exhibiting a sudden change in resilience in response to movement of the second shaft, the resilient means including a buckled spring running through the transverse hole in the first shaft and a triangular element fastened to the buckled spring in line with the second shaft, thereby providing tactile feedback to the user.
 7. An actuating mechanism as in claim 6 wherein the switch means comprises: a conductive element, a spring and a support member formed from a single piece of material, the conductive element being suspended by the spring from the support member, the conductive element being positioned in line with the first shaft, and the support member being attached to the guiding means; and a circuit element supported in line with the first shaft and the conductive element, whereby depression of the key causes the first shaft to displace the conductive element with respect to the circuit element. 